Devices have been disclosed for mounting and aligning optical elements such as lenses for coupling light from laser diodes to optical fibers in an optical system. Prior art devices for mounting and aligning optical elements typically lack contact between the parts and supporting structure, thus necessitating the use of a filler material to bridge the gap between the optical element and the substrate, as well as some form of the adhesive to attach the filler to the optic and the substrate. In many cases, the same material performs the filler and adhesive functions. For example, in one prior art device, the lens is bonded to the substrate using an ultraviolet-curing epoxy. Once the lens is moved into position, a droplet of the liquid adhesive is added to fill the gap between the lens and the substrate, giving a filler with a shape determined largely by surface tension effects. The adhesive is cured with UV irradiation to create a solid filler that is attached to both surfaces. Typically these adhesive layer has a thickness ranging from 20 to 50 microns. Longer-term stability is generally limited by the dimensional instabilities, especially in the presence of residual stresses, temperature cycling or humidity. Designs based on this technique are well known for their tendency to creep over time.
Prior art mounting devices are described, for example, in U.S. Pat. No. 4,749,250 to Carter, U.S. Pat. No. 4,842,391 to Kim et al., U.S. Pat. No. 4,498,737 to Doggett, and U.S. Pat. No. 4,752,109 to Gordon et al. These prior art techniques use relatively bulky macro-sized elements which are not compatible with miniature assemblies. U.S. Pat. No. 6,416,937 to Flanders et al. describes a miniature holder where flexural elements are permanently deformed by an external alignment mechanism to provide multi-axis alignment. This technique requires expensive fabrication equipment and techniques for fabricating the holder and complicated iterative techniques for deforming the flexural elements.
In general, it is an object of the invention to provide a microassembly and method for positioning microelements.